This week President Bush arrives accompanied by a massive entourage of advisers and security staff. London will be more disrupted for this state visit than for any other.

The Stop the War Coalition has organised a whole series of meetings, film shows, debates and demonstrations to enable the ordinary public to express their feelings.

The contrast could not be greater: of a president being feted (at a cost of £4m) and refusing to answer a question or debate anything, while the peace movement has had to argue every inch of the way for the right to hold marches and demonstrations. Since 2001 we have had constantly to assert our right to be heard against those who would silence us.

The strange question is why Mr Bush is coming at all. And whose idea was it to invite him?

No US president has ever had a state visit before, only as head of government. As a first-term, controversially appointed head of state, Mr Bush should hardly be the first choice.

Mr Bush and Mr Blair are defined politically by the Iraq war. It is clear that Mr Bush needs Mr Blair so that he can claim some international support for his lawless activities, his open contempt for the UN and for the legal processes relating to the incarceration of prisoners.

Quite what calculation has led Mr Blair to need Mr Bush so much is less obvious. After September 11 there was understandable shock around the world, followed by a short period of taking stock. Then Mr Bush pronounced a war of retribution against Afghanistan, followed by the "axis of evil" speech.

Mr Blair's initial reaction was similar to that of most other European heads of government, but then it went much further. As the build-up to the Iraq war began, Mr Bush arrogantly assumed that he could do what he liked. After all, he is commander in chief, and in international affairs, unlike nationally, he has a pretty free hand.

Mr Blair's position, on the other hand, is much tighter. He has had to answer questions at least once a week and thus provide some rational explanation for the campaign against Iraq. This has been his undoing as even his most ardent supporters have had trouble following the shifting sands of WMDs, missiles, al-Qaida links and reinterpretations of history.

Tony Blair got his vote in March, and lost his credibility in foreign policy at the same time. With perhaps 10,000 Iraqis dead, US soldiers dying at an alarming rate and international organisations and "allies" pulling out fast, one asks: where are we going now?

Far from making the world a safer place, Mr Bush has learned no lessons from history, appears incapable of understanding the world's cultural diversity and thinks crony capitalism is synonymous with democracy.

On Sunday night I watched the film Born on the Fourth of July in the company of Ron Kovic, its hero in real life. The story is that of a man's journey from unquestioning patriotism and faith in military strength, via dead children in Vietnamese villages, horrific injuries and contemptible treatment of Vietnam veterans to his destination as an indefatigable peace campaigner.

Mr Bush looks and sounds more like Nixon did in the 1970s, as the US people gear up to oppose him. This visit will be seen as a strange mistake - it is now of no benefit to Mr Blair or Mr Bush, but has been a huge boost to the transatlantic peace movement.